Abstract

Use of the shield with the blowing agent has been 20 years of history , especially over the past decade the bubbles to improved soil practices gaining the attention of engineering session , the range of applications and increasing scale , but by a number of factors bubble additives using mostly stay on the basis of experience with the construction , theoretical research is not enough . Not a clear set of procedures to detect the effect of foaming agent and bubbles soil improvement , some foreign research organizations are actively pursuing research in this area , and there are no relevant published . At present, a variety of blowing agents used in domestic Shield Tunnel mostly foreign imports , higher cost , similar foaming agent products for the research and development stage , and not put into use . Therefore , in the face of various brands of foam products , a corresponding set of bubbles in the evaluation of the effectiveness of the shield tunneling , the contractor is a reasonable choice to apply to the product of the foaming agent is of great significance to detect product developers the performance of the product is an essential tool . Above , the following research : (1) for earth pressure balance shield , due to poor soil properties caused by the construction problems , analyze the soil suitable for pressure balance shield construction pressure chamber soil ideal state - \expansion ratio and the indoor foam test found to affect these two indicators of the main factors for the concentration of the foaming agent solution ; (3) blowing agent used for the earth pressure balance shield blindness , bubble improved soil \foam agent performance evaluation methods, and by comparison of the results of laboratory tests and field tests to verify the applicability of this method .